Ink jet dye design

ABSTRACT

Magenta chromophore dyes which are stabilized by adding steric hindering groups to protect the imino carbons; nonlimiting examples of the steric hindering groups being phenyl, methyl, ethyl, isopropyl, fluoride, chloride, bromide and iodide groups.

FIELD OF THE INVENTION

[0001] The present invention generally relates to ink-jet printing, andin particular to a specific dye and ink sets for improving ink-jet printstability.

BACKGROUND OF THE INVENTION

[0002] Inkjet printing is a non-impact printing process in whichdroplets of ink are deposited on a print medium in a particular order toform alphanumeric characters, area-fills, and other patterns thereon.Low cost and high quality of the hardcopy output, combined withrelatively noise-free operation, have made ink-jet printers a popularalternative to other types of printers used with computers.Notwithstanding their recent success, intensive research and developmentefforts continue toward improving ink-jet print quality. A surge ininterest in ink-jet printing has resulted in the need to produce highquality prints at a reasonable cost. The challenge remains to furtherimprove the print quality and lightfastness of ink-jet prints. Theemerging use of ink-jet prints for digital photos, requireshigh-resolution images that have accurate color and are durable.

[0003] Manufacturers of photographic film and print media have come upwith dyes reported to have a display life of up to 60 years. A search ofpatents by Fuji revealed that they have developed a class of dyes, whichwhen used in photographic media, are very stable. However, this class ofdyes has been found not to be very stable toward light. Lightfastness isa very important quality in a dye used in ink-jet printing. Further, itis known that these azopyrazolone dyes can be attacked by ozone at theimine carbon. These shortcoming of such known photographic dyes,especially in the magenta and magenta-containing colors, make themunsuitable for use in ink-jet printing.

[0004] Accordingly, investigations continue into developing inkformulations which have improved properties and which do not improve oneproperty at the expense of the others. Thus, there remains a need in theart to further improve the print quality, color gamut, and lightfastnessof the ink-jet prints without sacrificing pen performance andreliability, particularly when trying to reproduce the color gamut ofsilver halide prints.

SUMMARY OF THE INVENTION

[0005] The present invention relates to a magenta ink for ink-jetprinting, comprising a dye having a structure as follows:

[0006] R2 is selected from the group consisting of methyl, ethyl,propyl, isopropyl and halogen;

[0007] R3 is selected from the group consisting of H, SO₃H, COOH, and apolyether group

[0008] where n is from 2 to 100;

[0009] R4 is selected from the group consisting of H, SO₃H, COOH,CH₂SO₃H, CH₂COOH, C₂H₄SO₃H and C₂H₄COOH;

[0010] R5 is selected from the group consisting of ethyl, propyl,isopropyl, phenyl, substituted phenyl and R4; and

[0011] R6 is selected from the group consisting of H, halogen, methyl,amino, substituted amino, R4 and R3.

[0012] The present invention also relates to a magenta ink for ink-jetprinting, comprising a dye having the following structure:

[0013] wherein R1 is selected from the group consisting of ethylisopropyl, isobutyl, phenyl and substituted phenyl;

[0014] R2 is selected from the group consisting of methyl, ethyl,propyl, isopropyl and halogen;

[0015] R3 is selected from the group consisting of H, SO₃H, COOH, and apolyether group

[0016] where n is from 2 to 100; and

[0017] R4 is selected from the group consisting of H, SO₃H, COOH,CH₂SO₃H, CH₂COOH, C₂H₄SO₃H and C₂H₄COOH.

[0018] In addition the present invention relates to a magenta ink forink-jet printing, comprising a dye having the following structure:

[0019] wherein m and n are from 0 to 4 added carbons.

[0020] Furthermore the present invention relates to a magenta ink forink-jet printing comprising a dye having the following structure:

[0021] is an azo dye structure

[0022] wherein A is selected from H and SO₃H,

[0023] or a gamma acid based dye structure

[0024] wherein A is selected from H and SO₃H.

[0025] The present invention also relates to a method for ink-jetprinting, comprising:

[0026] providing at least one magenta ink containing at least onemagenta dye having a visible light absorbance of 0.01 to 0.57 atlambda_(max) at a 1:10,000 dilution in water and having a structure asfollows:

[0027] R2 is selected from the group consisting of methyl, ethyl,propyl, isopropyl and halogen;

[0028] R3 is selected from the group consisting of H, SO₃H, COOH, and apolyether group

[0029] where n is from 2 to 100;

[0030] R4 is selected from the group consisting of H, SO₃H, COOH,CH₂SO₃H, CH₂COOH, C₂H₄SO₃H and C₂H₄COOH;

[0031] R5 is selected from the group consisting of ethyl, propyl,isopropyl, phenyl, substituted phenyl, and R4; and

[0032] R6 is selected from the group consisting of H, halogen, methyl,amino, substituted amino, R4 and R3.

[0033] ; and

[0034] printing said ink on a printing medium by means of an ink-jetpen.

[0035] In addition the present invention relates to a method for ink-jetprinting, comprising:

[0036] providing at least one magenta ink containing at least onemagenta dye having a visible light absorbance of 0.01 to 0.57 atlambda_(max) at a 1:10,000 dilution in water and having a structure asfollows:

[0037] wherein R1 is selected from the group consisting of ethylisopropyl, isobutyl, phenyl and substituted phenyl;

[0038] R2 is selected from the group consisting of methyl, ethyl,propyl, isopropyl and halogen;

[0039] R3 is selected from the group consisting of H, SO₃H, COOH, and apolyether group

[0040] where n is from 2 to 100; and

[0041] R4 is selected from the group consisting of H, SO₃H, COOH,CH₂SO₃H, CH₂COOH, C₂H₄SO₃H and C₂H₄COOH.

[0042] ; and

[0043] printing said ink on a printing medium by means of an ink-jetpen.

[0044] Furthermore, the present invention relates to a method forink-jet printing, comprising:

[0045] providing at least one magenta ink containing at least onemagenta dye having a visible light absorbance of 0.01 to 0.57 atlambda_(max) at a 1:10,000 dilution in water and having a structure asfollows:

[0046] wherein m and n are from 0 to 4 added carbons.

[0047] ; and

[0048] printing said ink on a printing medium by means of an ink-jetpen.

[0049] Additionally the present invention relates to a method forink-jet printing, comprising:

[0050] providing at least one magenta ink containing at least onemagenta dye having a visible light absorbance of 0.01 to 0.57 atlambda_(max) at a 1:10,000 dilution in water and having a structure asfollows:

[0051] is an azo dye structure

[0052] wherein A is selected from H and SO₃H,

[0053] or a gamma-acid based dye structure

[0054] wherein A is selected from H and SO₃H

[0055] ; and

[0056] printing said ink on a printing medium by means of an ink-jetpen.

[0057] Also the present invention relates to a method of stabilizingchromophore dyes containing imino groups, the imino groups selected fromthe group consisting of imino groups A and B:

[0058] the method comprising adding steric groups to protect iminocarbons, the steric groups being selected from phenyl, methyl, ethyl,isopropyl, fluoride, chloride, bromide and iodide.

[0059] Furthermore, the present invention relates to a method ofstabilizing chromophore dyes comprising arms ending in at least one ofcyanuric and melamine groups:

[0060] wherein m and n are from 0 to 4 added carbons.

[0061] the method comprising forming intramolecular hydrogen bondsbetween the cyanuric and melamine groups:

[0062] wherein m and n have from 0 to 4 added carbons.

[0063] Also, the present invention relates to a method of stabilizingchromophore dyes with one of the following structures comprising armsending in at least one of cyanuric and melamine groups:

[0064] the method comprising forming intermolecular hydrogen bondsbetween the cyanuric and melamine groups of two different dye molecules:

[0065] is an azo dye structure

[0066] wherein A is selected from H and SO₃H

[0067] or a gamma acid based dye structure

[0068] wherein A is selected from H and SO₃H.

DETAILED DESCRIPTION OF THE INVENTION

[0069] The invention described herein is directed to dyes for use withcommercially available ink-jet printers such as Design Jet® linerprinters, manufactured by Hewlett-Packard Company, of Palo Alto, Calif.More specifically, a specific dye for formulating the magenta isdisclosed. The dye enables the production of high-quality print andexcellent lightfastness. The inks formulated according to the inventionproduce images having color appearance that meets commercialrequirements for color accuracy and durability.

[0070] One of the most stable photographic systems on the market todayis Fuji film and print media, which is reported to have a display lifeof 60 years. A search of patents by Fuji revealed that they havedeveloped a novel class of dyes, which when used in photographic media,were very stable. Structures 1 and 2 are examples of such dyes:

[0071] Recognizing that the environment around the dye plays a verylarge role in dye stability, HP isolated the magenta dye from developedFuji Crystal Archive photographic media and investigated its stabilityon a typical glossy ink jet medium. It was found not to be very stabletoward light. Further, it is known that these azopyrazolone dyes can beattacked by ozone at the imine carbon. Thus, at first glance, this classof dye does not appear to be very interesting from an ink jetapplication standpoint. However, given that the chemistry of this classof dye is well known and it has a very good color, it is an excellentchoice to pursue the concept of steric protection.

[0072] If all of the large “ballast” groups are stripped away that arepresent in typical photographic dyes to leave the basic chromophore andattach groups to provide steric protection of the imine carbon, the dyesshown in Structures 3 and 4 are produced

[0073] In structure 3, the phenyl group attached to the imino N at C-4has ortho-methyl groups, which will inhibit formation of tetrahedral Nduring ozonolysis. Similarly, the C-5 nitrogen has two phenyl groupswith ortho chlorines attached to make approach to C-5 more difficult. Inan analogous manner, the azopyrasolotriazole dye (structure 2) has beenmodified to produce structure 4. In addition to the same ortho-methylgroups on the imino phenyl ring, oxygen at C-8 has an isopropyl insteadof an ethyl group.

[0074] Molecular modeling (Hyperchem) of structure 3 shows that theapproach to the imine carbon (or to the entire pyrazolone ring) is veryhindered. Structure 1 shows the energy minimized structure.

[0075] A remaining challenge is to make these dyes water-soluble. Twooptions appear likely. One is to sulfonate one or more of the aromaticrings. Second is to change the acetamide groups to contain awater-solubilizing group, such as COOH, SO₃H, or polyether.

[0076] Further, it has been reported that spiroindane compounds whenadded to solutions of these dyes improve their lightfastness. It isspeculated that the spiro materials act as singlet excited statequenchers. Thus, similar type additives could be added to these dyeseither in the ink or in the media itself. Such work is the subject of arecent patent application by the same inventor, Ser. No. 09/662,950filed on Sep. 15, 2000.

[0077] Another approach to providing steric protection of dyes is toencase them inside some structure. One method of doing this is toconstruct bridges that cross over above and below the imine or azoplane. However, synthetically, such structures are very challenging tomake. An alternate method of doing this is to use the concept of“self-assembly”. In this approach, the dye is constructed so that itcontains arms that spontaneously form bridge like structures. This areaof chemistry is extensive and recently reviewed. The driving force tomake the bridge structure is the formation of several hydrogen bonds,although other methods such as metal chelation are also possible.

[0078] Using a prototypical acid azo dye, complementary arms can beattached so that they form hydrogen bonds with each other. This processforms the protecting bridge. Such a structure is shown in structure 5,where the cyanuric and melamine groups can form H-bonds to each otherabove and below the plane of the naphthalene ring. This effectively“encapsulates” the dye. Space filling models (HGS) show that thisarrangement is possible.

[0079] wherein m and n are from 0 to 4 added carbons.

[0080] An alternate approach to this methodology is to shorten the alkylchains that attach the cyanuric acid groups. This precludesintra-molecular H-bonding to the melamine group, but allowsinter-molecular H-bonding. A head to tail stacking of the dye moleculesthen results. This enforced aggregation of the dye protects the dye forobvious steric reasons. Further, dye aggregation has been shown toimprove light stability. This stacked structure is shown in Structure 6.

[0081] is an azo dye structure

[0082] wherein A is selected from H and SO₃H,

[0083] or a gamma acid based dye structure

[0084] wherein A is selected from H and SO₃H.

[0085] The present magenta aqueous ink compositions each comprise ingeneral from about 0.1 to about 5 wt % of at least one dye, and avehicle comprising the following components (in wt % of total inkcomposition): from about 5 to about 30 wt % of at least one organicsolvent; 0 to about 2.0 wt % of at least one component independentlyselected from the group consisting of surfactants, buffers, biocides,and metal chelators; and the balance water.

[0086] All concentrations herein are in weight percent of total inkcomposition unless otherwise indicated. The purity of all components isthat employed in normal commercial practice for ink-jet inks.

[0087] Vehicle

[0088] The inks of the present invention comprise an aqueous vehiclecomprising the following components (in wt % of total ink composition):from about 5 to about 30 wt % of at least one water soluble organicsolvent; 0 to about 2.0 wt % of at least one component independentlyselected from the group consisting of surfactants, buffers, biocides,and metal chelators; and the balance water.

[0089] Organic Solvent

[0090] The inks of the present invention comprise from about 5 to about30 wt % organic solvent. More preferably, the inks comprise from about 8to about 20 wt % organic solvent, with a concentration from about 9 toabout 15 wt % being the most preferred. The water soluble organicsolvents suitably employed in the present ink-jet ink compositionsinclude any of, or a mixture of two or more, of such compounds asnitrogen-containing heterocyclic ketones, such as 2-pyrrolidone,N-methyl-pyrrolid-2-one (NMP), 1,3-dimethylimidazolid-2-one, andoctyl-pyrrolidone; diols such as ethanediols, (e.g., 1,2-ethandiol),propanediols (e.g., 1,2-propanediol, 1,3-propanediol,2-ethyl-2-hydroxy-methyl-1,3-propanediol, ethylhydroxy-propanediol(EHPD), butanediols (e.g., 1,2-butanediol, 1,3-butanediol,1,4-butanediol), pentanediols (e.g., 1,2-pentanediol, 1,5-pentanediol),hexanediols (e.g., 1,6-hexanediol, 2,5-hexanediol, 1,2-hexanediol),heptanediols (e.g., 1,2-heptanediol, 1,7-heptanediol), octanediols(e.g., 1,2-octanediol, 1,8-octanediol); glycols and thioglycols,commonly employed in ink-jet inks, such as polyalkylene glycols such aspolyethylene glycols (e.g., diethylene glycol (DEG), triethylene glycol,tetraethylene glycol), polypropylene glycols (e.g., dipropylene glycol,tripropylene glycol, tetrapropylene glycol), polymeric glycols (e.g.,PEG 200, PEG 300, PEG 400, PPG 400), and thiodiglycol; and glycol etherssuch as dipropylene glycol monobutyl ether, propylene glycol monobutylether, and ethylene glycol monobutyl ether, diethylene glycol monohexylether.

[0091] Surfactant

[0092] The inks of the present invention optionally comprise 0 to about2.0 wt % surfactant. More preferably, the inks comprise from about 0.1to about 1.8 wt % surfactant, with a concentration from about 0.8 toabout 1.5 wt % being the most preferred.

[0093] In the practice of the invention, one or more surfactants mayoptionally be used. Non-ionic surfactants, such as secondary alcoholethoxylates (e.g., Tergitol series available from Union Carbide Co.),non-ionic fluoro surfactants (e.g., FC170C available from 3M, non-ionicfatty acid ethoxylate surfactants (e.g., Alkamul PSMO-20 available fromRhone-Poulenc), non-ionic silicone surfactants (e.g., SilwetL7600available from Osi Specialties, Inc. Danbury, Conn.), and fatty amideethoxylate surfactants (e.g., Aldamide L203 available fromRhone-Poulenc) are preferred, with secondary alcohol ethoxylates beingthe most preferred. In the practice of the invention, the surfactantserves to prevent color to color bleed by increasing the penetration ofthe inks into the print medium, and to improve the spread of the ink onpolymer coated media. Secondary alcohol ethoxylates are nonionicsurfactants and are commercially available, for example, from UnionCarbide Co. (Houston, Tex.) as the Tergitol series, such as Tergitol15-S-5 and Tergitol 1 5-S-7.

[0094] The secondary alcohol ethoxylates contain (a) an aliphatic chainhaving a prescribed number of carbon atoms in the chain, and (b) aprescribed number of ethoxylated units. These ethoxylates arecommercially available as mixtures of ethoxylates, and so are describedin terms of the predominance of a given compound. Secondary alcoholethoxylates suitably employed in the practice of the inventionpredominantly have from about 12 to about 18 carbon atoms in thealiphatic chain, while the number of ethoxylated units is predominantlyin the range of from about 4 to about 8 units. Thus, “Tergitol 15-S-5”represents a secondary alcohol ethoxylate surfactant predominantlyhaving about 15 carbons in its aliphatic chain and about 5 ethoxylatedunits. Tergitol 15-S-5 and Tergitol 15-S-7 are the preferredsurfactants.

[0095] Buffer

[0096] The inks of the present invention optionally comprise 0 to about1.5 wt % buffer. More preferably, the inks comprise from about 0.1 toabout 0.5 wt % buffer, with a concentration from about 0.1 to about 0.3wt % being the most preferred. Buffers employed in the practice of theinvention to modulate pH can be organic-based biological buffers orinorganic buffers, preferably, organic-based. Further, the buffersemployed should maintain a pH ranging from about 3 to about 9 in thepractice of the invention, preferably about 6.5 to about 8 and mostpreferably from about 7.5 to 8.5. Examples of preferably-employedbuffers include Trizma Base, available from companies such as AldrichChemical (Milwaukee, Wis.), 4-morpholineethanesulfonic acid (MES),b-hydroxy-4-morpholinepropanesulfonic acid (MOPSO), and4-morpholinepropanesulfonic acid (MOPS).

[0097] Metal Chelator

[0098] The inks of the present invention optionally comprise 0 to about1.5 wt % metal chelator. More preferably, the inks comprise from about0.1 to about 0.5 wt % metal chelator, with a concentration from about0.1 to about 0.3 wt % being the most preferred.

[0099] Metal chelators employed in the practice of the invention areused to bind transition metal cations that may be present in the ink.Examples of preferably-employed metal chelators include:Ethylenediaminetetraacetic acid (EDTA), Diethylenetriaminepentaaceticacid (DTPA), trans-1,2-diaminocyclohexanetetraacetic acid (CDTA),(ethylenedioxy) diethylenedinitrilotetraacetic acid (EGTA), or otherchelators that can bind transition metal actions. More preferably, EDTA,and DTPA; and most preferably EDTA in its disodium salt form is employedin the practice of the invention.

[0100] Biocide

[0101] The inks of the present invention optionally comprise 0 to about1.5 wt % biocide. More preferably, the inks comprise from about 0.1 toabout 0.5 wt % biocide, with a concentration from about 0.1 to about 0.3wt % being the most preferred.

[0102] Any of the biocides commonly employed in ink-jet inks may beemployed in the practice of the invention, such as Nuosept 95, availablefrom Huls America (Piscataway, N.J.); Proxel GXL, available from Zeneca(Wilmington, Del.); and glutaraldehyde, available from Union CarbideCompany (Bound Brook, N.J.) under the trade designation Ucarcide 250.Proxel GXL is the preferred biocide.

[0103] The specific ink set disclosed herein is expected to findcommercial use in ink-jet color printing.

EXAMPLES Example 1

[0104] A pyrazolone azomethine dye dye of the present invention, issynthesized as shown below:

[0105] The desired hindered phenylenediamine is made by treating2,5-dimethyl-1,4-phenylenediamine with methyl-3-chloropropanante andhydrolyzing the resulting ester to the acid. In the above formula, thepyrazolone azomethine dye [4-(3-methyl-4-)4-(N,N-di-(ethylsulfonicacid)amino)-1-phenylimino)-5-oxo-2-pyrazolin-yl)-benzoic acid] wasprepared by adding 0.6 grams of potassium persulfate to a stirredmixture of 4-(3-methyl-5-oxo-2-pyrazolin-1-yl)-benzoic acid (1 mmol),N,N-di-ethylsulfonic acid)-1,4-phenylenediamine (0.25 g), methanol (10mL), and sodium carbonate in water (5%; 20 mL). The mixture was stirredfor about 40 minutes and then additional water (70 mL) was added. Thepyrazolone azomethine dye was collected by filtration, dried andrecrystallized with methanol or ethanol.

What is claimed is:
 1. A magenta ink for ink-jet printing, comprising adye having a structure as follows:

R2 is selected from the group consisting of methyl, ethyl, propyl,isopropyl and halogen; R3 is selected from the group consisting of H,SO₃H, COOH, and a polyether group

where n is from 2 to 100; R4 is selected from the group consisting of H,SO₃H, COOH, CH₂SO₃H, CH₂COOH, C₂H₄SO₃H and C₂H₄COOH; R5 is selected fromthe group consisting of ethyl, propyl, isopropyl, phenyl, substitutedphenyl, and R4; and R6 is selected from the group consisting of H,halogen, methyl, amino, substituted amino, R4 and R3.
 2. A magenta inkaccording to claim 1, wherein the dye has a structure as follows:

R2 is selected from the group consisting of methyl, ethyl, propyl,isopropyl and halogen; R3 is selected from the group consisting of H,SO₃H, COOH, and a polyether group

where n is from 2 to 100; R4 is selected from the group consisting of H,SO₃H, COOH, CH₂SO₃H, CH₂COOH, C₂H₄SO₃H and C₂H₄COOH; and R5 is selectedfrom the group consisting of ethyl, propyl, isopropyl, phenyl,substituted phenyl, and R4.
 3. A magenta ink according to claim 1,wherein the dye has a structure as follows:

wherein R2 is selected from the group consisting of methyl, ethyl,propyl, isopropyl and halogen; R3 is selected from the group consistingof H, SO₃H, COOH, and a polyether group

where n is from 2 to 100; and R4 is selected from the group consistingof H, SO₃H, COOH, CH₂SO₃H, CH₂COOH, C₂H₄SO₃H and C₂H₄COOH.
 4. A magentaink according to claim 1, wherein the dye has a structure as follows:


5. The magenta ink of claim 1 wherein said magenta ink comprises fromabout 0.5 to about 6 wt % dye.
 6. The magenta ink of claim 5 whereinsaid magenta ink comprises from about 0.5 to about 4 wt % dye.
 7. Theink of claim 1 further comprising: about 5 to about 30 wt % of at leastone organic solvent; 0 to about 2.0 wt % of at least one componentindependently selected from the group consisting of surfactants,buffers, biocides, and metal chelators.
 8. The ink of claim 1, having avisible light absorbance of 0.01 to 0.57 at lambda_(max) and at a1:10,000 dilution in water.
 9. A magenta ink for ink-jet printing,comprising a dye having the following structure:

wherein R1 is selected from the group consisting of ethyl isopropyl,isobutyl, phenyl and substituted phenyl; R2 is selected from the groupconsisting of methyl, ethyl, propyl, isopropyl and halogen; R3 isselected from the group consisting of H, SO₃H, COOH, and a polyethergroup

where n is from 2 to 100; and R4 is selected from the group consistingof H, SO₃H, COOH, CH₂SO₃H, CH₂COOH, C₂H₄SO₃H and C₂H₄COOH.
 10. Themagenta ink of claim 9 wherein the dye has the following structure:


11. The magenta ink of claim 9 wherein said magenta ink comprises fromabout 0.5 to about 6 wt % dye.
 12. The magenta ink of claim 11 whereinsaid magenta ink comprises from about 0.5 to about 4 wt % dye.
 13. Theink of claim 9 further comprising: about 5 to about 30 wt % of at leastone organic solvent; 0 to about 2.0 wt % of at least one componentindependently selected from the group consisting of surfactants,buffers, biocides, and metal chelators.
 14. The ink of claim 9, having avisible light absorbance of 0.01 to 0.57 at lambda_(max) and at a1:10,000 dilution in water.
 15. A magenta ink for ink-jet printing,comprising a dye having the following structure:

wherein m and n are from 0 to 4 added carbons.
 16. The magenta ink ofclaim 15 wherein said magenta ink comprises from about 0.5 to about 6 wt% dye.
 17. The magenta ink of claim 16 wherein said magenta inkcomprises from about 0.5 to about 4 wt % dye.
 18. The ink of claim 15further comprising: about 5 to about 30 wt % of at least one organicsolvent; 0 to about 2.0 wt % of at least one component independentlyselected from the group consisting of surfactants, buffers, biocides,and metal chelators.
 19. The ink of claim 15, having a visible lightabsorbance of 0.01 to 0.57 at lambda_(max) and at a 1:10,000 dilution inwater.
 20. A magenta ink for inkjet printing comprising a dye having thefollowing structure:

is an azo dye structure

wherein A is selected from H and SO₃H, or a gamma acid based dyestructure

wherein A is selected from H and SO₃H.
 21. The magenta ink of claim 20wherein said magenta ink comprises from about 0.5 to about 6 wt % dye.22. The magenta ink of claim 21 wherein said magenta ink comprises fromabout 0.5 to about 4 wt % dye.
 23. The ink of claim 20 furthercomprising: about 5 to about 30 wt % of at least one organic solvent; 0to about 2.0 wt % of at least one component independently selected fromthe group consisting of surfactants, buffers, biocides, and metalchelators.
 24. The ink of claim 20, having a visible light absorbance of0.01 to 0.57 at lambda_(max) and at a 1:10,000 dilution in water.
 25. Amethod for ink-jet printing, comprising: providing at least one magentaink containing at least one magenta dye having a visible lightabsorbance of 0.01 to 0.57 at lambda_(max) at a 1:10,000 dilution inwater and having a structure as follows:

wherein R2 is selected from the group consisting of methyl, ethyl,propyl, isopropyl and halogen; R3 is selected from the group consistingof H, SO₃H, COOH, and a polyether group

where n is from 2 to 100; R4 is selected from the group consisting of H,SO₃H, COOH, CH₂SO₃H, CH₂COOH, C₂H₄SO₃H and C₂H₄COOH; R5 is selected fromthe group consisting of ethyl, propyl, isopropyl, phenyl, substitutedphenyl, and R4; and R6 is selected from the group consisting of H,halogen, methyl, amino, substituted amino, R4 and R3; and printing saidink on a printing medium by means of an ink-jet pen.
 26. The methodaccording to claim 25, wherein the structure of the magenta dye is asfollows:

wherein R2 is selected from the group consisting of methyl, ethyl,propyl, isopropyl and halogen; R3 is selected from the group consistingof H, SO₃H, COOH, and a polyether group

where n is from 2 to 100; R4 is selected from the group consisting of H,SO₃H, COOH, CH₂SO₃H, CH₂COOH, C₂H₄SO₃H and C₂H₄COOH; and R5 is selectedfrom the group consisting of ethyl, propyl, isopropyl, phenyl,substituted phenyl, and R4.
 27. The method according to claim 25,wherein the structure of the magenta dye is as follows:

wherein R2 is selected from the group consisting of methyl, ethyl,propyl, isopropyl and halogen; R3 is selected from the group consistingof H, SO₃H, CO OH, and a polyether group

where n is from 2 to 100; and R4 is selected from the group consistingof H, SO₃H, COOH, CH₂SO₃H, CH₂COOH, C₂H₄SO₃H and C₂H₄COOH.
 28. Themethod according to claim 25, wherein the structure of the magenta dyeis as follows:


29. A method for ink-jet printing, comprising: providing at least onemagenta ink containing at least one magenta dye having a visible lightabsorbance of 0.01 to 0.57 at lambda_(max) at a 1:10,000 dilution inwater and having a structure as follows:

wherein R1 is selected from the group consisting of ethyl isopropyl,isobutyl, phenyl and substituted phenyl; R2 is selected from the groupconsisting of methyl, ethyl, propyl, isopropyl and halogen; R3 isselected from the group consisting of H, SO₃H, COOH, and a polyethergroup

where n is from 2 to 100; and R4 is selected from the group consistingof H, SO₃H, COOH, CH₂SO₃H, CH₂COOH, C₂H₄SO₃H and C₂H₄COOH; and printingsaid ink on a printing medium by means of an ink-jet pen.
 30. The methodaccording to claim 29 wherein the structure of the magenta dye is asfollows:


31. A method for ink-jet printing, comprising: providing at least onemagenta ink containing at least one magenta dye having a visible lightabsorbance of 0.01 to 0.57 at lambda_(max) at a 1:10,000 dilution inwater and having a structure as follows:

wherein m and n are from 0 to 4 added carbons. and printing said ink ona printing medium by means of an ink-jet pen.
 32. A method for ink-jetprinting, comprising: providing at least one magenta ink containing atleast one magenta dye having a visible light absorbance of 0.01 to 0.57at lambda_(max) at a 1:10,000 dilution in water and having a structureas follows:

is an azo dye structure

wherein A is selected from H and SO₃H, or a gamma acid based dyestructure

wherein A is selected from H and SO₃H. ; and printing said ink on aprinting medium by means of an ink-jet pen.
 33. A method of stabilizingchromophore dyes containing imino groups, the imino groups selected fromthe group consisting of imino groups A and B:

the method comprising adding steric groups to protect imino carbons, thesteric groups being selected from phenyl, methyl, ethyl, isopropyl,fluoride, chloride, bromide and iodide.
 34. The method of claim 33wherein the imino group A is protected by at least one methyl groupattached ortho to an imino N-attached phenyl group:


35. The method of claim 33 wherein the imino group A is protected by atleast one phenyl group with at least one ortho chlorine attached:


36. The method of claim 33 wherein the imino group B is protected by atleast one phenyl group with at least one methyl group attached:


37. The method of claim 33 wherein the imino group B is protected by atleast one O-attached isopropyl group:


38. A method of stabilizing chromophore dyes comprising arms ending inat least one of cyanuric and melamine groups:

wherein m and n are from 0 to 4 added carbons. the method comprisingforming intramolecular hydrogen bonds between the cyanuric and melaminegroups

wherein m and n are from 0 to 4 added carbons.
 39. A method ofstabilizing chromophore dyes with one of the following structurescomprising arms ending in at least one of cyanuric and melamine groups:

the method comprising forming intermolecular hydrogen bonds between thecyanuric and melamine groups of two different dye molecules:

is an azo dye structure

or a gamma acid based dye structure